Sequential mass spectrometry applied to monitoring the modulation of microbial secondary metabolites

Author(s)

Talita Carla de Tralia Medeiros

• Document type: Doctoral Thesis
• Press: Ribeirão Preto.
• Institution: Universidade de São Paulo (USP). Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto (PCARP/BC)
• Defense date: 2025-02-07

Examining board members

Luiz Alberto Beraldo de Moraes; Anelize Bauermeister; Edson Rodrigues Filho; Carla Porto da Silva

• Advisor: Luiz Alberto Beraldo de Moraes

Abstract

Actinobacteria are renowned for producing a wide variety of biologically active compounds, and several strategies have been explored to modulate the production of secondary metabolites in these microorganisms. This study aims to investigate the modulation of bioactive compound production by actinobacteria, focusing on strategies for the production of antibiotics and antifungals active against phytopathogens. Morphological characterization of the isolate CAAT 8-25 was performed using SEM, and partial sequencing of the 16S rRNA gene was conducted. Differentiation between microorganisms was achieved through MALDI fingerprinting and metabolomic studies. Five major compounds produced by the isolate were identified as responsible for its biological activity against phytopathogenic bacteria and fungi: oxytetracycline, herbicidin K, herbicidin F, rimocidin, and rimocidin aglycone. Five distinct strategies were applied to study the modulation of bioactive compound production: OSMAC (cultivation in different media), the addition of metals and rare earth elements, mixed cultures, co-cultivation, and the inclusion of pro-inflammatory compounds in the culture medium. Experiments were analyzed using mass spectrometry with various analyzers, including triple quadrupole, Q-TOF, LTQ, and Orbitrap. Additionally, the molecular networking technique was employed as a tool for analyzing and identifying new metabolites and/or analogs of known compounds, offering a detailed metabolomic approach. The combination of these techniques, including ambient ionization mass spectrometry with continuous flow extraction, enabled precise analysis of the compounds. Moreover, the spatial distribution of metabolites was investigated using DESI-IMS with the imprint technique. (AU)

• FAPESP's process: 18/03782-3 - Sequential mass spectrometry applied to the monitoring of induction of bioactive molecules in microbial co-culture
• Grantee: Talita Carla de Tralia Medeiros
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)